And unlike most epidemiological studies on omega-3s and brain health, it involved people in mid-adulthood, aged 35 to 54 … so the evidence it provides is especially interesting.
Relatively few studies have examined the effects of omega-3s in this “young middle age” bracket, with mixed but generally favorable results (Kalmijn S et al. 2004; Fontani G et al. 2005; Eskelinen MH et al. 2008; Devore EE et al. 2009).
We’ve also reported on other evidence that omega-3s may enhance brain health and performance in people from 20 to 50:
Let’s take a look at the new findings, which add force to the increasing calls for clinical trials.
Blood analysis links omega-3 DHA to better brain function in middle age
Researchers from the University of Pittsburgh analyzed health records and blood tests from 280 people aged 35 to 54 (Muldoon MF et al. 2010).
The participants were mentally and physically healthy, and were not taking fish oil or omega-3 supplements. Thus, the omega-3s in their blood came from foods.
The analysis sought associations between blood levels of three different omega-3 fatty acids—ALA, EPA, and DHA—and five measures of cognitive functioning, based on the results of neuropsychological tests.
(EPA and DHA are the long-chain omega-3s found in fish fat, while ALA is the short-chain omega-3 found in green plants. The body burns most dietary ALA for its calories, and converts only about two to 10 percent of it into EPA and DHA… the two omega-3s proven essential to child development, key immune functions, and brain and eye health.)
Specifically, the Pittsburgh team was looking to see whether higher blood levels of any of these three omega-3 fats were associated with better or worse “non-verbal reasoning” and “working” memory in people between 35 and 54.
Non-verbal reasoning is the ability to identify relationships between shapes and patterns, visual sequences, and objects. Working memory is required for the integration, processing, disposal, and retrieval of information.
Of the three omega-3s, DHA is most closely associated with brain function. DHA constitutes some 60 percent of the fat in the brain, and it’s a key structural and functional component of brain cell membranes.
And as we would have expected, DHA was the winner: “[A] higher DHA [blood level] was related to better performance on tests of nonverbal reasoning and mental flexibility, working memory, and vocabulary” (Muldoon MF et al. 2010).
Importantly, the researchers detected a “dose-response” relationship between omega-3 DHA and better brain function… a finding that raises the likelihood that omega-3 DHA really was responsible for the brain benefits the scientists observed.
In contrast, higher blood levels of EPA and ALA were not associated with better cognitive performance. This is not very surprising, since neither of these omega-3 fatty acids is as closely associated as DHA with brain health.
The authors had this to say about the significance of their results: “These findings suggest that DHA is related to brain health throughout the lifespan...” (Muldoon MF et al. 2010).
That is, in addition to helping deter, delay, or diminish dementia among people aged 65 or more, omega-3 DHA from fish fat may boost basic brain powers in younger adults.
Authors call for more research
As we note below (see “Why this epidemiological study was better than most”), this kind of study has limitations… a caveat the authors expressed:
“The findings from these analyses… cannot establish that any association between the omega-3 fatty acids cognitive performance is causal” (Muldoon MF et al. 2010).
Accordingly, even as they affirmed the existence of considerable evidence for the presumed brain benefits of omega-3s, they underlined the need for clinical trials:
“While this and prior observational studies of omega-3 fatty acids and cognitive function have generally found [positive] associations [with brain health] that withstand adjustment for obvious confounding [diet/lifestyle] factors… randomized clinical trials in both healthy and clinical [populations] are warranted.” (Muldoon MF et al. 2010)
Is anyone in charge at NIH listening? We hope so!
Why this epidemiological study was better than most
In all but a few epidemiological studies, people are surveyed about their eating habits in order to estimate their intake of a nutrient being studied for possible health effects... in this case, omega-3s.
The accuracy of this approach relies on several factors prone to error: the quality of the diet survey and the omega-3-intake estimates it yields, the size of the study population, the number of years being recalled… and people’s fuzzy memories.
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Devore EE, Grodstein F, van Rooij FJ, Hofman A, Rosner B, Stampfer MJ, Witteman JC, Breteler MM. Dietary intake of fish and omega-3 fatty acids in relation to long-term dementia risk. Am J Clin Nutr. 2009 Jul;90(1):170-6. Epub 2009 May 27.
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Eskelinen MH, Ngandu T, Helkala EL, Tuomilehto J, Nissinen A, Soininen H, Kivipelto M. Fat intake at midlife and cognitive impairment later in life: a population-based CAIDE study. Int J Geriatr Psychiatry. 2008 Jul;23(7):741-7.
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Fontani G, Corradeschi F, Felici A, Alfatti F, Bugarini R, Fiaschi AI, Cerretani D, Montorfano G, Rizzo AM, Berra B. Blood profiles, body fat and mood state in healthy subjects on different diets supplemented with Omega-3 polyunsaturated fatty acids. Eur J Clin Invest. 2005 Aug;35(8):499-507.
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Fontani G, Corradeschi F, Felici A, Alfatti F, Bugarini R, Fiaschi AI, Cerretani D, Montorfano G, Rizzo AM, Berra B. Blood profiles, body fat and mood state in healthy subjects on different diets supplemented with Omega-3 polyunsaturated fatty acids. Eur J Clin Invest. 2005 Aug;35(8):499-507.
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Kalmijn S, van Boxtel MP, Ocké M, Verschuren WM, Kromhout D, Launer LJ. Dietary intake of fatty acids and fish in relation to cognitive performance at middle age. Neurology. 2004 Jan 27;62(2):275-80.
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Morris MC, Evans DA, Tangney CC, Bienias JL, Wilson RS. Fish consumption and cognitive decline with age in a large community study. Arch Neurol. 2005 Dec;62(12):1849-53. Epub 2005 Oct 10.
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Muldoon MF, Ryan CM, Sheu L, Yao JK, Conklin SM, Manuck SB. Serum Phospholipid Docosahexaenonic Acid Is Associated with Cognitive Functioning during Middle Adulthood. J Nutr. 2010 Feb 24. [Epub ahead of print] doi:10.3945/jn.109.119578
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van de Rest O, Spiro A 3rd, Krall-Kaye E, Geleijnse JM, de Groot LC, Tucker KL. Intakes of (n-3) fatty acids and fatty fish are not associated with cognitive performance and 6-year cognitive change in men participating in the Veterans Affairs Normative Aging Study. J Nutr. 2009 Dec;139(12):2329-36. Epub 2009 Oct 14.
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van Gelder BM, Tijhuis M, Kalmijn S, Kromhout D. Fish consumption, n-3 fatty acids, and subsequent 5-y cognitive decline in elderly men: the Zutphen Elderly Study. Am J Clin Nutr. 2007 Apr;85(4):1142-7.
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